title: The sulfhydryl groups responsible for bilitranslocase transport activity respond to the interaction of the carrier with bilirubin and functional analogues.
abstract: Both inactivation of sulfobromophthalein transport in rat liver plasma membrane vesicles by sulfhydryl group reagents and subsequent reactivation by 2-mercaptoethanol are shown to be modulated by ligands to bilitranslocase. In particular, bilirubin, sulfobromophthalein and Thymol blue behave as negative effectors in the inactivation reaction and as positive effectors in the reactivation reaction. Kinetic data provide further evidence of the existence of two classes of sulfhydryl groups involved in transport activity. The effect brought about by remarkably low concentrations of bilirubin is in line with the physiological function of bilitranslocase as a bilirubin carrier.
authors.affiliation: Dipartimento di Biochimica Biofisica e Chimica delle Macromolecole, Università degli Studi di Trieste, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Passamonti
authors.forename: G L
authors.initials: GL
authors.lastname: Sottocasa
mesh_terms: D000818:Animals; D001663:Bilirubin / Q000494:pharmacology*; D001693:Biological Transport, Active; D001979:Bromthymol Blue / Q000494:pharmacology; D002570:Ceruloplasmin; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D007700:Kinetics; D008565:Membrane Proteins / Q000032:analysis / Q000502:physiology*; D008623:Mercaptoethanol / Q000494:pharmacology; D051381:Rats; D013438:Sulfhydryl Compounds / Q000032:analysis; D013448:Sulfobromophthalein / Q000494:pharmacology
chemical_list: D008565:Membrane Proteins; D013438:Sulfhydryl Compounds; D013448:Sulfobromophthalein; D008623:Mercaptoethanol; D004228:Dithionitrobenzoic Acid; D002570:Ceruloplasmin; C033838:bilitranslocase; D005033:Ethylmaleimide; D001663:Bilirubin; D001979:Bromthymol Blue